Thursday, 16 July 2009

The Eagle Has Landed—Two Men Walk on the Moon

Today is a momentous day. In case you live in a hole you should know that today is the 40th Anniversary of the Apollo 11 mission. The infamous moon landing. The mission fulfilled President John F. Kennedy's goal of reaching the moon by the end of the 1960s, which he expressed during a speech given before a joint session of Congress on May 25, 1961

"I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth."

Each crewmember of Apollo 11 had made a spaceflight before this mission, making it the second all-veteran crew in manned spaceflight history. Collins was originally slated to be the Command Module Pilot (CMP) on Apollo 8 but was removed when he required surgery on his back and was replaced by Jim Lovell, his backup for that flight. After Collins was medically cleared he took what would have been Lovell's spot on Apollo 11.

In the spring of 1969 Bill Anders accepted a job with the National Space Council effective in August 1969 and had announced his retirement as an astronaut. At that point Ken Mattingly was moved from the support crew into parallel training with Anders as backup Command Module Pilot in case Apollo 11 was delayed past its intended July launch (at which point Anders would be unavailable if needed) and would later join Lovell's crew and ultimately be assigned as the original Apollo 13 CMP.

A Saturn V launched Apollo 11 from the Kennedy Space Center on July 16, 1969 at 13:32 UTC (9:32 a.m. local time). It entered orbit 12 minutes later.[1]After one and a half orbits, the S-IVB third-stage engine pushed the spacecraft onto its trajectory toward the Moon with the Trans Lunar Injection burn. About 30 minutes later the command/service module pair separated from this last remaining Saturn V stage and docked with the lunar module still nestled in the Lunar Module Adaptor.

On July 19 Apollo 11 passed behind the Moon and fired its service propulsion engine to enter lunar orbit. In the thirty orbits[5] that followed, the crew saw passing views of their landing site in the southern Sea of Tranquility (Mare Tranquillitatis) about 20 kilometers (12 mi) southwest of the crater Sabine D (0.67408N, 23.47297E). The landing site was selected in part because it had been characterized as relatively flat and smooth by the automated Ranger 8 and Surveyor 5 landers along with the Lunar Orbiter mapping spacecraft and unlikely to present major landing or extra-vehicular activity (EVA) challenges.
On July 20, 1969 the lunar module (LM) Eagle separated from the command module Columbia. Collins, alone aboard Columbia, inspected Eagle as it pirouetted before him to ensure the craft was not damaged.
As the descent began, Armstrong and Aldrin found that they were passing landmarks on the surface 4 seconds early and reported they were "long". They would land miles west of their target point. The LM navigation and guidance computer distracted the crew with several unusual "1201" and "1202" program alarms. Inside Mission Control Center in Houston, Texas, computer engineer Jack Garman told guidance officer Steve Bales it was safe to continue the descent and this was relayed to the crew. When Armstrong again looked outside, he saw that the computer's landing target was in a boulder strewn area just north and east of a 400 meter diameter crater (later determined to be "West crater", named for its location in the western part of the originally planned landing ellipse). Armstrong took semi-automatic control[7] and with Aldrin calling out altitude and velocity data, landed at 20:17 UTCon July 20 with about 25 seconds of fuel left.

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